1. Field of the Invention
The present invention relates generally to tracking fingertip movement, and in particular, to a method, apparatus, and article of manufacture for precisely tracking the location of fingertips during a medical examination. More specifically, the location is tracked while the fingertips palpate physical structures or manipulate appendages during medical exams or therapies.
2. Description of the Related Art
(Note: This application references a number of different publications as indicated throughout the specification by reference numbers enclosed in brackets, e.g., [x]. A list of these different publications ordered according to these reference numbers can be found below in the section entitled “References.” Each of these publications is incorporated by reference herein.)
During the course of medical examinations, therapies, or surgeries, medical doctors in a very wide variety of medical specialties palpate physical structures or manipulate joints, bones, or appendages. For example, recognizable points of a human skeleton may be palpated, range-of-motion measurements may be conducted, and fractured bones may be reduced using a physician's fingers. Further, many areas of medicine require a physician or medical specialist to measure the size and depth of physical structures for the purposes of diagnosis of injury or disease, planning therapeutic interventions, or monitoring the patient recovery process. Despite the fact that such measures are made and recorded literally millions of time per day, it is current practice for physicians to estimate or guesstimate the size of critical dimensions based on fingertip placements. Such measurements are often only accurate to 30%. Nonetheless, such measurements are routinely used for diagnosis, treatment planning, assessing treatment outcomes, and as the basis for clinical trials that assess the validity of new treatments. Moreover, such data is often the basis for disability insurance reimbursements legal remuneration for injury.
These problems may be better understood with an explanation of prior art medical examination techniques and computer-assisted tracking methodologies.
Medical Examination Techniques
In the practice of orthopedics, the ability to palpate recognizable points of the human skeleton is an essential skill for diagnosis and treatment. Skeletal bones have consistent protrusions that aid the examiner in localizing the bone in order to frame the rest of the examination. For example, the medial and lateral epincondyles of the knee, along with the perimeter of the patella and the tibial tubercle create a framework from which the examiner can palpate adjacent ligamentous structures such as the medial collateral ligament and the knee menisci. FIG. 1 illustrates the prominent bony landmarks around the knee and up to the hip. Similarly, the medial and lateral epicondyles of the elbow, and radial and ulnar styloids of the forearm are prominent points that define the distal humerus and forearm. FIG. 2 illustrates the prominent bony landmarks around the elbow. In the shoulder as illustrated in FIG. 3, the posterior corner of the acromion, the coracoid, the inferior angle and the scapular spine can easily be accessed to generate a representation of this bone.
The cluster of points that represent a given bone are informative in their own right but can also form a foundation that can be used in a variety of ways. For example, accurate representation of the skeleton provides the basis for defining the relative motion between any adjacent skeletal segments. If the two segments are connected, the range of motion so measured defines the range of motion of the interposed joint. Thus, on its own, skeletal information provides a three dimensional representation of size and proportion of each skeletal segment. Taken together, data of multiple bones begins to define the size and proportion characteristics that distinguish one individual from another. Precise information of these individual differences has great application to many fields and is largely inaccessible in other ways with the exception of radiography. This information has import not only to clinical medicine, but also to fields as disparate as clothes manufacturing and game development using motion capture technology.
As described above, measuring joint range-of-motion is an integral part of clinical orthopedics. Range of motion measurements are a standard part of nearly every orthopedic exam. FIG. 4 illustrates skeletal landmarks used to construct a local coordinate system to define the range of motion with precision. In FIG. 4A, planes of elevation for a scapular based coordinate system are shown from a superior view. In FIG. 4B, the angle of elevation is shown with respect to a scapular reference. FIG. 4C illustrates a global diagram based on a scapular coordinate system showing rotation (45°) referenced to the latitude. Typically, the examiner moves a joint through its range of motion and makes a visual estimate of the angular changes observed. For more precise measurements, it is customary to lay a transparent goniometer next to the joint to determine this angle. However, problems with accuracy, intra and inter observer variability, are widely known and discussed in the medical literature.
Accurate skeletal information is also vital in performing computer-assisted reduction of fractured bones. The clinical practice of fracture reduction involves the identification of a fracture by X-ray, then the application of reduction principles, some form of fixation to the aligned skeletal segment, and finally, post-reduction X-rays to confirm fracture reduction. The principles of fracture reduction consistently recommend longitudinal traction of the fractured segment while applying corrective forces to recreate the normal alignment of the segment. FIG. 5 illustrates the manipulation of broken bones: femur in FIG. 5A and elbow in FIG. 5B, that can be guided by re-establishing relative alignment of bony landmarks above and below the fracture (by comparing to the other side for example). The normal alignment of the segment is estimated by the clinician, in part by his or her knowledge of anatomy, and to a much greater extent by comparison to the patient's unaffected, opposite side. For some applications, this reduction process is performed under fluoroscopy.
Computer Assisted Tracking Methodologies
The human fingertip (FT) typically has the discriminative tactile ability to distinguish points as near as 2-5 millimeters, depending on the individual, (innate capabilities, degree of training, callous formation, etc.). Various tracking technologies (electromagnetic, optical, or other) exist in the prior art. Examples of such prior art technologies are described in U.S. Pat. Nos. 3,868,565, 3,983,474, 4,017,858, 4,988,981, 5,047,942, and U.S. patent application Ser. No. 2002/0198472, which patents and applications are incorporated by reference herein. Further devices that provide tracking of movements may also be available in the prior art (e.g., the electromagnetic measurement system from Ascension Technology described at www.ascension-tech.com, a measurement system from Polhemus described at www.polhemus.com, and/or the skeleton builder from Motion Analysis Corporation described at www.motionanalysis.com, which information is incorporated by reference herein).
Various types of computer-assisted methodologies may be used in the medical field. For example, references [1]-[31] describe some of the various medical fields that utilize some form of computer-assisted tracking.
However, such prior art methodologies lack numerous beneficial attributes, are not flexible, and have many disadvantages. For example, many prior art devices merely utilize a wand to track movements. Alternatively, prior art devices may not provide the level of granularity necessary in the medical context, and/or fail to allow the flexibility to conduct measurements using real-world movements of an examiner. In this regard, none of the prior art technologies enable or utilize a human user's ability to localize points through touch, position, and pressure sense. In addition, the prior art devices commonly merely deliver tactile information to the fingertip to mimic tactile experience, a field known as haptics in virtual reality technologies. Such mimicking fails to allow the user to freely navigate the real world around them using their own perceptual abilities to assess their surroundings.
Accordingly, what is needed is a device and methodology for tracking an examiner's real-world movements during a medical examination, procedure, and/or therapy.